Merges to android Pi release (part: 1)

Below are a set of CLs being merged from the wv cdm repo to the android repo.

* Fix handling of OEM Cert public key.

  Author: Srujan Gaddam <srujzs@google.com>

  [ Merge of http://go/wvgerrit/27921 ]

  This is a potential fix for b/36656190. Set aside public
  key on first call to get the public key, and use it afterwards.
  This gets rid of extra calls to OEMCrypto_GetOEMPublicCertificate(),
  which has side-effect of staging the OEM private key.

  This also fixes a problem where the public cert string was
  not being trimmed to match the size returned by
  OEMCrypto_GetOEMPublicCertificate().

* Complete provisioning request/response for Provisioning 3.0

  Author: Gene Morgan <gmorgan@google.com>

  [ Merge of http://go/wvgerrit/27780 ]

  Fix bug on provisioning request path where GenerateDerivedKeys()
  was being called when preparing to generate the signature.

  Add message signature verification, and call correct OEMCrypto
  routine to rewrap the private key (OEMCrypto_RewrapDeviceRSAKey30).

* Implement Cdm::deleteAllUsageRecords()

  Author: Gene Morgan <gmorgan@google.com>

  [ Merge of http://go/wvgerrit/27780 ]

  Delete all usage records for current origin.  Removes usage
  records from file system and retains the PSTs.  The deletes
  any usage entries matching those PSTs held by OEMCrypto.

  BUG: 35319024

* Remove stringencoders library from third_party.

  Author: Jacob Trimble <modmaker@google.com>

  [ Merge of http://go/wvgerrit/27585 ]

  We have a fork of the stringencoders library that we use for base64
  encoding.  This reimplements base64 encoding to remove the extra
  dependency and to reduce the amount of code.

* Add Cdm::deleteUsageRecord() based on key_set_id.

  Author: Gene Morgan <gmorgan@google.com>

  [ Merge of http://go/wvgerrit/27605 ]

  Delete specified usage record from file system usage info and
  from OEMCrypto.

  BUG: 35319024

* Modifiable OEMCrypto

  Author: Fred Gylys-Colwell <fredgc@google.com>

  [ Merge of http://go/wvgerrit/24729 ]

  This CL adds a new variant of the OEMCrypto mock code that adjusts its
  behavior based on a configuration file.  This is intended for
  testing.

  For example, a tester can set current_hdcp to 2 in the options.txt
  file, push it to the device, and verify that a license is granted for
  HDCP 2.0.  Then the tester can edit the value of current_hdcp to 1 and
  push the file to the device.  Playback should stop because the license
  is no longer valid.

  This variant uses a real level 1 liboemcrypto.so to push data to a
  secure buffer.  That means we can test playback for a license that
  requires secure buffers on an Android device with real secure buffers.

  BUG: 35141278
  BUG: 37353534

BUG: 71650075
Test: Not currently passing. Will be addressed in a subsequent
      commit in the chain.

Change-Id: I58443c510919e992bb455192e70373490a00e2b6

libwvdrmengine/cdm/core/src/device_files.proto

@@ -44,7 +44,6 @@ message License {
   // ignored if there is no grace period.
   optional int64 grace_period_end_time = 11 [default = 0];
   optional bytes usage_entry = 12;
-  optional int64 usage_entry_number = 13;
 }
 
 message UsageInfo {
@@ -54,7 +53,6 @@ message UsageInfo {
     optional bytes license = 3;
     optional bytes key_set_id = 4;
     optional bytes usage_entry = 5;
-    optional int64 usage_entry_number = 6;
   }
 
   repeated ProviderSession sessions = 1;
@@ -74,12 +72,12 @@ message UsageTableInfo {
     enum UsageEntryStorage {
       LICENSE = 1;
       USAGE_INFO = 2;
-      UNKNOWN = 3;
     }
 
     optional UsageEntryStorage storage = 1;
-    optional bytes key_set_id = 2;
-    optional bytes usage_info_file_name = 3; // hash of the app_id
+    optional bytes key_set_id = 2;  // used if storage is LICENSE
+    optional bytes provider_session_token = 3;  // used if storage is USAGE_INFO
+    optional bytes app_id = 4; // used if storage is USAGE_INFO
   }
 
   optional bytes usage_table_header = 1;